/Engine/Source/Runtime/Engine/Classes/Materials/Material.h
Add an expression node that represents a parameter to the list of material parameters.
virtual bool AddExpressionParameter ( [UMaterialExpression](API\Runtime\Engine\Materials\UMaterialExpression) * Expression, [TMap](API\Runtime\Core\Containers\TMap)< [FName](API\Runtime\Core\UObject\FName), [TArray](API\Runtime\Core\Containers\TArray)< [UMaterialExpression](API\Runtime\Engine\Materials\UMaterialExpression) * > > & ParameterTypeMap )